Synchronous Digital Hierarchy Synchronous Optical Network SDH/SONET

Telecommunication Networks GroupTechnische Universität Berlin

Synchronous Digital HierarchySynchronous Optical NetworkSDH/SONET

Filip IdzikowskiHagen Woesner

Berlin, 31.05.2007

TKN Telecommunication Networks GroupSDH/Sonet, Berlin, 31.05.2007

2

OverviewMotivationSDH/SONET LayeringGeneral Concept of SDH

Analogy to a railway trainSDH data streams and containersMultiplexingClockingAdaptation

Addressing + justificationExamples

SDH/SONET devicesMultiplexersRegeneratorsDigital Crossconnects

Ring structuresSummary


3

Literature

Mike Sexton, Andy Reid: "Transmission Networking: SONET and the Synchronous Digital Hierarchy", Artech House, Boston /London, 1992Sławomir Kula „Systemy Teletransmisyjne”, Wydawnictwa Komunikacji i Łączności, Warszawa, 2004


4

MotivationTo overcome drawbacks of PDH

Need for inbuilt management mechanismsLack of free bits in frames to send system informationLack of automatic protection systemsLack of fast, dynamic and automatic reconfiguration of the networkDifficulties while sending signals incompatible with PDH hierarchyHigh energy consumption and low reliability of cascade multiplexersLack of standards for optical interfacesMany different standards for plesiochronous hierarchy

Synchronous systemsTransmission speed of an output signal is assumed to match the overall data rates of multiplexed signalsMost popular nowadays despite the need for precise clocks


5

Layering – SDH/SONET terminology

MUX MUX DEMUXMUXR R

WD

M

WD

M

RS RS RS RS RS

Multiplex Section (MS) Multiplex Section (MS) MS

Higher Order Path (HOP) HOP

Lower Order Path (LOP)

Digital Path

Optical Section (OS)

General goal of SDH/SONET:

Fast transmission of information on a digital path.

PathHigher/Lower Order Path

LineMultiplex section

SectionRegeneration section

SONETSDH


6

The concept of SDH on an example

C-4

POH VC-4 = C-4 +

+ Path Overhead (POH)

VirtualContainer

VC-4PTR AU-4 = VC-4 + + Pointer (PTR)

AdministrativeUnit

C-4 Container C-4

Input signal e.g. ATM cells


7

The concept of SDH (2)

Synchronous Transport Module (STM)STM-1 = AUG-4 + SOH, where SOH = RSOH + MSOH

VC-4PTRRSOH

MSOH

STM-1#n

AU-1 AUG-4 = 1 x AU-1

VC-4PTRRSOH

MSOH

STM-1#n-1

VC-4PTRRSOH

MSOH

STM-1#n-2

AdministrativeUnit Group

Overhead

Payload

time


8

Synchronous Transport Module (STM-1)

9 columns 261 columns

5 rows

1 row

3 rows

Duration of a frame: 125 µs

STM-1 corresponds to the basic data rate in SDH:

9 · 270 · 8 bit / 125 µs = 155.52 Mbit/s

- Administrative Unit Group AUG-n

Multiplex Section Overhead (MSOH)

PayloadAdministrative Unit Pointer (AU-PTR)

Regenerator Section Overhead (RSOH)


9

Synchronous Transport Module (STM-n)

9N columns 261N columns

5 rows

1 row

3 rows

Each byte in a frame creates a transmission channel with data rate:

P = 8 [bit]/125 [µs] = 64 kb/s (voice channel!!!))

- Administrative Unit Group AUG-n

Multiplex Section Overhead (MSOH)

PayloadAdministrative Unit Pointer (AU-PTR)

Regenerator Section Overhead (RSOH)


10

Synchronous Transport Module STM-1

FunctionByte(s)

Engineering Orderwire Service (EOW)E1, E2

Transmission medium type∆

transmission error detection (Binary Interleaved Parity – BIP) BIP-8 for RSOH, and BIP-24 for MSOH

B1, B2

Access Point Identifier (APId) – identifies the receiverJ0

frame phasing formulaA1, A2

FunctionByte(s)

feedback information about block errorsM1

Quality of Synchronization ClockS1

Information about Automatic Protection Switching (APS)K1, K2

Data Communication Channel (DCC) – Management System (ISP dependant! Bytes in RSOH and MSOH!)

D1-D12

User’s channel – unspecified usage in International StandardsF1

XXE2M1S1

D12D11D10

D9D8D7

D6D5D4

K2K1B2B2B2

PayloadPTR-AU

D3∆D2∆∆D1

XXF1∆E1∆∆B1

XXJ0A2A2A2A1A1A1

- Regeneration Secion Overhead (RSOH) - Multiplex Secion Overhead (RSOH)


11

SDH Containers

C-11, C-12, C-2, C-3Lower Order Containers

C-3, C-4, C-4-4-c, C-4-16c, C-4-64c, C-4-256cHigher Order Containers

Bas

ic

con

tain

ers

C-3 may be a Lower Order Container or a Higher Order ContainerRecall: a Virtual Container = a Container + Path Overhead

VC-n = C-n + POH

„c” stands for concatenated (not multiplexed) containers


12

Higher Order Virtual Container (VC-4, VC-3)

N1

K3

F3

H4

F2

PayloadG1

C2

B3

J1

Information about Automatic Protection Switching (APS)K3

Engineering Orderwire Service (EOW)H4

Signal label (stores information about signal that was mapped into VC-n)

C2

FunctionByte(s)

Management of Tandem ConnectionsN1

User’s channel – mainly for managementF2, F3

Path Status (feedback information sent in reverse direction)

G1

transmission error detection (BIP-8)B3

Termination Element Identifier (coded)J1

9 ro

ws

261 columns (VC-4) / 85 columns (VC-3)

- Path Overhead (POH)

Tandem connections - connections that are established via networks belonging to different Internet Service Providers


13

Lower Order Virtual Containers

Payload J2 Payload N2 Payload K4 PayloadV5

Management of Tandem ConnectionsN2

FunctionByte(s)

Information about Automatic Protection Switching (APS)K4

Termination Element IdentifierJ2

transmission error detection (BIP-2), signal label, Path Status

V5

1 ro

w25

34

106

- Path Overhead (POH)

VC-11

VC-12

VC-2

25

34

106

25

34

106

25

34

106Amou

nt

of b

ytes

Lower Order Virtual Containers are alligned to Tributary Units (and later to Tributary Unit Groups), what corresponds to Administrative Unit (AU) and Administrative Unit Group (AUG) fo Higher Virtual Order ContainersConcatenated containers are similar to presented Virtual Containers regarding system management


14

SDH - multiplexingNo overhead bits needed for justificationHigher speed link is formed by byte-interleaving data from lower speed linksExact multiples of lower speed data rates (e.g. STM-4 contains exactly 4 byte-interleaved STM-1 frames)Just very small buffers needed due to byte-interleaving and synchronism

STM-1

STM-1

STM-1

STM-1

STM-4


15

SDH - multiplexing

9510.9129621.5049953.28STM-64OC-19210

38043.64838486.01639813.12STM-256OC-76811

2377.7282405.3762488.32STM-16OC-489

1783.2961804.0321866.24STM-12OC-368

1188.8641202.6881244.16STM-8OC-246

891.648902.12933.12STM-6OC-185

594.824601.344622.08STM-4OC-124

445.824451.008466.56STM-3OC-93

148.608150.336155.52STM-1OC-32

49.53650.11251.84-OC-11

Data rate (user)

Data rate (AUG)

Data rate (gross)

Europe(SDH), Japan

US (SONET)Level

OC – Optical ChannelSTM – Synchronous Transport ModuleAUG – Administrative Unit GroupSPE – Synchronous Payload Envelope = AU in SDH


16

SDH - clockingIn the ideal case, all network elements are totally synchronousExpensive clocks and synchronization networks are needed

A rubidium-clock with short-term (10 s) stability of 5·10-12÷ 5·10-11

costs < 10000 $ (year 2004)A ceasium-clock with short-term (10 s) stability of 5·10-11 and no linear frequency drift costs 25000 ÷ 50000$ (year 2004)

Still, there are differencies in the clock rates of different devicesDelay variance of 5·10-10 means that two tributaries differ in one frame length every 3 daysNeed of adaptation of signals to their nominal rates

Put the tributaries into containersLet the container start anywhere in the payload frame (Addressing)Keep and manage the movement of pointer to theses containers, when adding the excessive bytes, or when byte stuffing (Justification)


17

SDH Multiplexing Structure – ITU-TSw

ww

.iec.org


18

Scenario – VC-4 in STM-1

FIFO

A B C

fBfA fC

STMA-1 STMB-1

………..….

Tl Tu

VC-4 VC-4

fIN fOUT

fIN may dynamically differ from fOUT

Three cases considered1. fIN = fNOMINAL – ideal synchronous case2. fIN < fNOMINAL – positive justification if threshold Tl exceeded3. fIN > fNOMINAL – negative justification if threshold Tu exceeded


19

Addressing

Pointer structure in Administrative Unit-4

H1 Y Y H2 1 1 H3H3H3- used bytes

- unused bytes

Pointer of AU-4

Justification

N N N N S S I D I D I D I D I D

AddressingBytes H1 and H2 store the location of VC-4 in the STM-1 Payload (precisely byte J1)Every third byte out of 2439 is addressed (1024 addresses stored in 10 I and D bits)

JustificationBytes H3 used for data transmission by negative justificationThree bytes R are inserted into the payload just behind the pointer by positive justification

N – new data flagS S – bits with constant 1 0 valueI D – addressing and justification

control

Adap

tatio

n


20

VC-4 in STM-1 – addressing

H3H3H311H2YYH1

VC-4

VC-4

H3H3H311H2YYH1

VC-4PO

H

J1

Address

J1

STM-1

# i

STM-1

# i+1

See slide 12 for the structure of VC-4


21

Creation of STM-1 – no justification

FIFO………..….

Tl Tu

fIN fOUT

VC-4RRR

RSOH, AU-PTR,MSOH

fOUT9 bytes 261 bytes

time

9 261 bytes

Payl

oad

(VC-

4)


22

VC-4 in STM-1 – no justification

H3H3H311H2YYH1

VC-4

VC-4

H3H3H311H2YYH1

VC-4PO

H

J1

Address

J1

STM-1

# i

STM-1

# i+1


23

Creation of STM-1 – positive justification

FIFO………..….

Tl Tu

fIN fOUT

VC-4RRR

`

RSOH, AU-PTR,MSOH


time

9 261 bytes 12 258 bytes

3 bytes R

R R R

Payl

oad

(VC-

4)


24

VC-4 in STM-1 – positive justification

H3H3H311H2YYH1

VC-4

VC-4

H3H3H311H2YYH1

VC-4PO

H

J1

Address

RRR

address + 1

J1

Positive

justification

STM-1

# i

STM-1

# i+1

Sign

allin

g of

ju

stifi

catio

nJu

stifi

catio

n


25

Creation of STM-1 – negative justification

FIFO………..….

Tl Tu

fIN fOUT

VC-4

RSOH, AU-PTR,MSOH


time


3 bytes from VC-4

Payl

oad

(VC-

4)


26

VC-4 in STM-1 – negative justification

H3H3H311H2YYH1

VC-4

VC-4

H3H3H311H2YYH1

VC-4PO

H

J1

Address

J1

address - 1

Negative

justification

STM-1

# i

STM-1

# i+1

Sign

allin

g of

ju

stifi

caio

nJu

stifi

caio

n


27

Example of a multiplexing scenario in SDH

Scenario:Each STM-1 frame carries three VC-3 containers with ATM cellsVC-3 containers are multiplexed into STM-1 payload with the use of adaptation mechanismThe rates of incoming stream of VC-3 containers differ slightly

MUX

VC-3

VC-3

VC-3

STM-1

3 VC-3s in STM-1


28

Steps in the multiplexing procedure

VC-3

Input data,

e.g. ATM cells

PTR AU-3

VC-3

Input data,

e.g. ATM cells

AU-3PTR

Input data,

e.g. ATM cells

VC-3

AU-3PTR

AUG-1PTR

3 Pointers showing the address of each VC-3, and signalling Pointer Justification Events (PJEs)!

MUX

STM-1

RSOH

MSOHSTM-1

VC-3

Two columnes of fixed stuff bytes


29

Pointer structureH1H1H1H2 H2H2H3H3H3

N N N N S S I D I D I D I D I D

AddressingBytes H1 and H2 store the location of VC-3 in the STM-1 Payload (precisely position of byte J1)Every possible position of J1 byte in STM-1 payload can be addressed (1024 addresses stored in 10 I and D bits, and the VC-3s are byte interleaved)

JustificationBytes H3 used for data transmission by negative justificationStuff bytes R are inserted into the payload just behind the pointer by positive justification

N – new data flagS S – bits with constant 1 0 valueI D – addressing and justification

control

Adap

tatio

n


30

3 x VC-3 in STM-1 – addressing

--------------------

--------------------

--------------------

H3H3H3H2H2H2H1H1H1

--------------------

--------------------

--------------------

--------------------

--------------------

H3H3H3H2H2H2H1H1H1

--------------------

Address 1

STM-1

# i

STM-1

# i+1

Address 3

Address 2

0 0 0 86 86 8629 29 29 58 58 58

3 x VC3 + 2x3x9 fixed stuff bytes (byte interleaved)

521521521

522522522

J1 J1 J1

782782782

875 µs

1000 µs

1125 µs

0 0 0 86 86 8629 29 30 58 58 58

521521521

523523523

783783783

Byte of the first VC-3 or corresponding fixed stuff

Byte of the second VC-3 or corresponding fixed stuff

Byte of the third VC-3 or corresponding fixed stuff

AU-3 PTR = a group consisting of a H1, H2 and H3 byte

STM-1 PTR = three groups consisting of a H1, H2 and H3 byte


31

Streams perf. synchronous – no justification

HOSM

bytes (byte interleaved)3 x VC-3 + 2x3x9 fixed stuff RRRH2H2H2H1H1H1

HOSR

9 bytes 261 bytes

time

9 261 bytes

FIFO………..….

fIN fOUT

TL TU

VC-3+ fixed stuff

FIFO………..….

TL TU

fIN fOUT

VC-3+ fixedstuff

FIFO………..….

TL TU

fIN fOUT

VC-3+ fixedstuff

RSOH, AU-PTR,MSOH

fOUT


32

3 x VC-3 in STM-1 – no justification

H3H3H3H2H2H2H1H1H1

H3H3H3H2H2H2H1H1H1

Address 1

STM-1

# i

STM-1

# i+1

Address 3

Address 2


J1 J1 J1

J1 J1 J1

875 µs

1000 µs

1125 µs


33

First stream too slow – positive justification

HOSM

bytes (byte interleaved)3 x VC-3 + 2x3x9 fixed stuff RRRH2H2H2H1H1H1

HOSR

fOUT

9 bytes 261 bytes

FIFO………..….

fIN fOUT

TL TU

VC-3+ fixed stuff

FIFO………..….

TL TU

fIN fOUT

VC-3+ fixedstuff

FIFO………..….

TL TU

fIN fOUT

VC-3+ fixedstuff

R

RSOH, AU-PTR,MSOH

time


1 byte R


34

Positive justification for the first stream

H3H3H3H2H2H2H1H1H1

H3H3H3H2H2H2H1H1H1

Address 1

STM-1

# i

STM-1

# i+1

Address 3

Address 2


J1 J1 J1

J1 J1

R

J1

(Address 1) + 1

875 µs

1000 µs

1125 µs

Sign

allin

g of

ju

stifi

caio

nJu

stifi

caio

n


35

First stream too fast – negative justification

HOSM

bytes (byte interleaved)3 x VC-3 + 2x3x9 fixed stuff RRH2H2H2H1H1H1

HOSR

RSOH, AU-PTR,MSOH

fOUT

9 bytes 261 bytes

FIFO………..….

fIN fOUT

TL TU

VC-3+ fixed stuff

FIFO………..….

TL TU

fIN fOUT

VC-3+ fixedstuff

FIFO………..….

TL TU

fIN fOUT

VC-3+ fixedstuff

time1 byte

9 261 bytes 6 261 bytes2


36

Negative justification for the first stream

H3H3H3H2H2H2H1H1H1

H3H3H2H2H2H1H1H1

Address 1

STM-1

# i

STM-1

# i+1

Address 3

Address 2


J1 J1 J1

875 µs

1000 µs

1125 µs

J1 J1 J1

(Address 1) - 1

Sign

allin

g of

ju

stifi

caio

nJu

stifi

caio

n


37

Demultiplexing

First 5 framesPosition of each input stream within the payload of STM-1 frame is identified with the address stored in the pointer. The receiver reads each address to find the position of each input stream in the output stream frame.

Subsequent framesThe receiver knows the addresses already, and updates (increments or decrements) it when an PJE happens.PJEs are signalled by negation of appropriate bits of the pointer

VC-3

VC-3

VC-3

STM-1 DEMUX


38

SDH/SONET devices

MultiplexersTerminal MultiplexersLine MultiplexersAdd Drop Multiplexers (ADMs)Transmultiplexers

RegeneratorsDigital Crossconnects (DXCs) or Digital CrossconnectSystems (DCSs)


39

Terminal and Line multiplexers

MultiplexersTerminal Multiplexers

Terminates connections on the Path layer – reads/writes Path Overhead (POH)Tributaries may be electrical or optical, e.g. map PDH streams into Virtual ContainersMay have switching capabilities

Line MultiplexersSimilar to terminal multiplexers, but operate just on the synchronous signals STM-N

MUX

2 Mb/s

34 Mb/s STM-N6 Mb/s

othersGbE


40

ADMs and TransmultiplexersMultiplexers

Add Drop Multiplexers (ADM)Terminates connections of the Multiplex Section (Line layer in SONET) - writes MSOH in SDH or LOH in SONETMay receive and transmit synchronous signals in two different directionsSignals may come also from outside of an SDH networkE.g. Add and drop an STM-1 to/from an STM-4

TransmultiplexersAllows transition of a Virtual Container 3 from AU-3 to TU-3 and vice versa (recall that VC-3 may be treated as a Higher Order Container and Lower Order Container)

STM-N STM-NADM

STM-M or signals outside of SDH


41

Regenerators

RegeneratorTerminates connections of the Regeneration Section (Section layer in SONET) – reads/writes just RSOH in SDH or SOH in SONETPerforms 3-R regeneration of signals (amplify, re-shape, re-clock) and opto/electro/optical conversionADMs and DXCs have the functionality of regenerators too.

Re.g. STM-4 STM-4


42

Digital CrossconnectsDigital Crossconnect System (DXC or DCS)

cross connects signals of different ordersHigher order DXC

HDXC switches only STM-1 framesDXC 4|4 means ”receive AU-4 and switch AU-4 granularity”

Lower order DXCLDXC mostly receive AU-4, but switch Tributary Units (TU)DXC 4|3|1 receives STM-1, but may switch VC=12, VC-3 and VC-4.

......

......

......

......

STM-4

STM-1

Tributaries (VC-12, VC-3)

STM-4

Digital Crossconnect System (DXC or DCS)cross connects signals of different ordersHigher order DXC

HDXC switches only STM-1 framesDXC 4|4 means ”receive AU-4 and switch AU-4 granularity”

Lower order DXCLDXC mostly receive AU-4, but switch Tributary Units (TU)DXC 4|3|1 receives STM-1, but may switch VC=12, VC-3 and VC-4.

DXC switches connections according to day-time changesCan be used to change network topology


43

Ring structures

Ring = bus with the interconnected terminating nodesGuarantees two alternative transmission paths => protection against link and node failuresMinimizes amount of links providing two alternative paths

SDH RingsReliability - reconfiguration of the ring within 50 ms (APS)

Maximum amount of nodes: 16Limited length (1200 km) ofa ring to lower propagationdelay and probability of failure


44

Categorization of SDH ring structures

Amount of rings in the structure and relationships between themDivision according to amount of fibres used in a ringDirection of transmission in a ringProtection mechanisms

The most popular structures are presented in the next slides


45

Unidirectional Self-Healing Ring (USHR)

One working ringOne protection ringStreams between nodes are sent just in one direction in a ring

ADMB

ADMA

ADMC

ADME

ADMD

Protection ring (2), STM-n

Working ring (1), STM-n

A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

21


46

USHR with path protection (USHR-PP)

Traffic sent in both rings in parallel – no need for signallingSignal from the protection ring may be received instead of the one from the working ring (1+1 protection)

ADMB

ADMA

ADMC

ADME

ADMD



A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

21


47

USHR with line protection (USHR-LP)

Signalling of alarm states done with bytes K1 and K2 of MSOH (Automatic Protection Switching channel)A backup ring is created in case of a failurePossible to send Low priority traffic in protection ring

ADMB

ADMA

ADMC

ADME

ADMD



A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

21


48

Bidirectional Self-Healing Ring (BSHR-2)

One reception ringOne transmission ringBandwidth of the rings divided into working part and protection part

ADMB

ADMA

ADMC

ADME

ADMD

Reception ring for A-C (2), STM-n

Transmission ring for A-C (1), STM-n

A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

21


49

BSHR-2 – line protection

Reconfiguration of nodes neighbouring the failureTime slot interchange neededPossible to send Low priority traffic in protection ring

ADMB

ADMA

ADMC

ADME

ADMD

A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

21

Transmission ring for A-C (1), STM-n

Reception ring for A-C (2), STM-n


50

Bidirectional Self-Healing Ring (BSHR-4)

Working BSHR-2Protection BSHR-2Two type of protections possible: link protection, and line (ring) protection

ADMB

ADMA

ADMC

ADME

ADMD

Protection ring STM-n

Working ring STM-n

A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

W1 W2 R1 R2

Transmission fiber (A-C)

Reception fiber (A-C)


51

BSHR-4 – span protection

Signalling with Automatic Protection Switching channelPotential low order traffic in Protection ring may be lost

ADMB

ADMA

ADMC

ADME

ADMD


Working ring STM-n

A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

W1 W2 R1 R2




52

BSHR-4 – line (ring) protection

Signalling with Automatic Protection Switching channelPotential low order traffic in Protection ring may be lost

ADMB

ADMA

ADMC

ADME

ADMD


Working ring STM-n

A-C

C-A

A-C

C-A

… …

…

ADMA

A-C

W1 W2 R1 R2




53

Summary

YesYesYesNoPossibility to send low priority traffic

SeparateCommonSeparateSeparateWorking and protection fibers

YesYesNoNoReuse of bandwidth

4222Amount of transmitter-receiver pars in a node

N x STM-nN/2 x STM-nSTM-nSTM-nMax. usable throughput

STM-nSTM-nSTM-nSTM-nThroughput

NNNNAmount of nodes

Line protection

Line protection

Line protection

Path protection

Type of protection against fiber failure

2111Amount of fiber pairs

BSHR-4BSHR-2USHR-LPUSHR-PPType of the ring


54

Multiring structures

Multiring structures allow an Internet Service Provider to build bigger and more robust topologiesConnection of separate ring structures by:

Sharing of two separate nodesHigher Layer rings

Protection schemes:Node protectionRing protection

Traffic between two neighbouring rings belonging to the same Layer may be:

carried by the neighbouring links themselvescarried by ring(s) belonging to higher layers


55

Two USHR-PP ring structure

ADME

ADMH

ADMB

ADMF

ADMA

2xADMC

2xADMD

ADMG

A-C

G-A

A-G A-C

G-A

A-G


56

Hierarchical structures

Node protection Ring protection

Traffic between Layer 1 rings carried by Layer 2

Layer 2Layer1

Layer 2

Layer1


57

Hierarchical structures

Node protection Ring protection

Traffic between neighbouring Layer 1 rings carried by Layer 1

Layer 2

Layer1Layer 2

Layer1


58

Summary (1)

Why are SDH rings so reliable?Reconfiguration time in 50 msAdaptation mechanisms against loss of synchronizationMany signalling channels available in the Overheads of STM’sand VC’s (also the ones that are not standardized and are free to use)Many versions and combinations of ring structures available (extension of the network range)Possibility to send low priority traffic in the protection rings, and to increase the utilization of the network


59

Summary (2)

SDH/SONET is the standard in the today’s backbone networksTransmission of data in streams with rates that are multiples of STM-1 (155.52 Mb/s) (51 Mb/s for SONET only)Physical layer was defined for copper and radio transmission media as well, but single mode fibre is mainly usedExtensive management and protection featuresHigh reliability due to high overprovisioningMappings of payload of different type into SDH/SONET frame has been defined – see the next lecture

IP over SONET, ATM over SONET etc.

Telecommunication Networks GroupTechnische Universität Berlin

Thank you for attention

Questions?

Synchronous Digital Hierarchy Synchronous Optical Network SDH/SONET

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